Absent Kate Stonesifer, classwork #19

Absent Kate Stonesifer, classwork #19 - and oxygen isotopes...

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Kate Stonesifer Astronomy 101 Mr. Shubert April 19, 2009 The CNO Cycle In a massive star the conversion of hydrogen into helium occurs through a process known as the CNO cycle which stands for Carbon-Nitrogen-Oxygen cycle. The CNO cycle requires a very high temperature to operate and therefore can only occur in the very center of the star. Also known as the Bethe-Weizsacker cycle it is one of the two sets of fusion reactions by which stars convert hydrogen into helium the other being the proton-proton chain. Theoretical models show us that the CNO cycle is the predominate source of energy in stars with a mass heavier than about 1.5 times the mass of the sun. In the CNO cycle, four protons fuse using carbon, nitrogen,
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Unformatted text preview: and oxygen isotopes as a catalyst a catalyst acts just like it does in the body where an enzyme causes a reaction to happen faster and more continuously to produce one alpha particle, two positrons, and two electron neutrinos. This is the same type of reaction that occurs in the massive star except its catalysts are carbon, nitrogen, and oxygen. The positrons will almost instantly annihilate with electrons, releasing energy in the form of gamma rays. The neutrinos escape from the star carrying away some of its energy. The carbon, nitrogen, and oxygen isotopes are really one nucleus combined that go through a number of transformations in an endless loop known as the CNO cycle....
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Absent Kate Stonesifer, classwork #19 - and oxygen isotopes...

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